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Reduction of oxalate levels in tomato fruit and consequent metabolic remodeling following overexpression of a fungal oxalate decarboxylase

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Title Reduction of oxalate levels in tomato fruit and consequent metabolic remodeling following overexpression of a fungal oxalate decarboxylase
 
Creator Chakraborty, Niranjan
Ghosh, Rajgourab
Ghosh, Sudip
Narula, Kanika
Tayal, Rajul
Datta, Asis
Chakraborty, Subhra
 
Description Accepted date: March 9, 2013
The plant metabolite oxalic acid is increasingly recognized as a food toxin with negative effects on human nutrition. Decarboxylative degradation of oxalic acid is catalyzed, in a substrate-specific reaction, by oxalate decarboxylase (OXDC), forming formic acid and carbon dioxide. Attempts to date to reduce oxalic acid levels and to understand the biological significance of OXDC in crop plants have met with little success. To investigate the role of OXDC and the metabolic consequences of oxalate down-regulation in a heterotrophic, oxalic acid-accumulating fruit, we generated transgenic tomato (Solanum lycopersicum) plants expressing an OXDC (FvOXDC) from the fungus Flammulina velutipes specifically in the fruit. These E8.2-OXDC fruit showed up to a 90% reduction in oxalate content, which correlated with concomitant increases in calcium, iron, and citrate. Expression of OXDC affected neither carbon dioxide assimilation rates nor resulted in any detectable morphological differences in the transgenic plants. Comparative proteomic analysis suggested that metabolic remodeling was associated with the decrease in oxalate content in transgenic fruit. Examination of the E8.2-OXDC fruit proteome revealed that OXDC-responsive proteins involved in metabolism and stress responses represented the most substantially up- and down-regulated categories, respectively, in the transgenic fruit, compared with those of wild-type plants. Collectively, our study provides insights into OXDC-regulated metabolic networks and may provide a widely applicable strategy for enhancing crop nutritional value.
This work was supported by grants from the Indian Council of
Medical Research (grant no. 63/2/2006–BMS) and the National Institute of Plant Genome Research, Government of India. R.G. and K.N.
were supported by a predoctoral fellowship from the Council for
Scientific and Industrial Research, Government of India.
 
Date 2015-11-02T08:54:06Z
2015-11-02T08:54:06Z
2013
 
Type Article
 
Identifier Plant Physiol., 162(1): 364-378
0032-0889
http://www.plantphysiol.org/content/162/1/364.long
http://172.16.0.77:8080/jspui/handle/123456789/299
 
Language en_US
 
Publisher American Society of Plant Biologists